激光熔覆Ni基复合涂层气孔及裂纹敏感性的研究

Research on Porosity and Cracking Sensitivity of Ni-based Composite Coating by Laser Cladding

对激光熔覆Ni基复合涂层内气孔的类型及形成机理,裂纹的形态、萌生机理及影响因素等进行了研究。结果表明,涂层内气孔出现在熔覆层表层及底层,气体主要来源于熔覆环境,也可能是熔覆过程中各组分相互反应而生成;裂纹从形态上分为垂直裂纹和水平裂纹两大类,其产生与熔覆层内的低熔共晶密切相关,涂层成分、夹杂物含量、激光比能对裂纹敏感性均有一定影响。

The types, formation mechanism of stomata and the morphology, initiation mechanism, influence factors of the crack on the Ni-based composite coating of laser cladding were studied. The results show that stomata coming from cladding environment or the interaction of the cladding process is found on the surface of cladding zone and upper area of bonding zone. There are two major categories of crack by the means of shape, vertical crack and horizontal crack, the generation of which is related to the low melting eutectic in the cladding area. The coating composition, contents of inclusion and laser specific energy all have influence on the cracking sensibility.